ABSTRACT
In this chapter, the authors review recent reports describing bacterial enzymes that degrade cellulose and hemicellulose and their genes and discuss their structures and functions. In cellulolytic bacteria and fungi, cellulase synthesis is usually regulated by induction and repression. Although several cellulase and hemicellulase genes, including xylanase genes, have been cloned, little is known about genetic modification of cellulolytic bacteria. For constructing shuttle vectors between the cellulolytic bacteria and E. coli, some plasmids were isolated from the rumen bacteria, such as Ruminococcus sp. Continuous culture, using antibiotic-free medium, shows that the expression of xylanase activity is extremely stable, with no demonstrated loss of the inserted xylanase gene over 60 generations. Furthermore, novel enzymes is important to understand the regulation of cellulase synthesis and to exploit new host-vector systems for gene manipulation in cellulolytic bacteria for the sake of using the enzymes for degradation of cellulosic material and the conversion of these substrates to usable forms of energy.
